assimp/include/assimp/irrXMLWrapper.h

/*
Open Asset Import Library (assimp)
----------------------------------------------------------------------

Copyright (c) 2006-2020, assimp team


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* Redistributions in binary form must reproduce the above
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*/

#ifndef INCLUDED_AI_IRRXML_WRAPPER
#define INCLUDED_AI_IRRXML_WRAPPER

// some long includes ....
#ifdef ASSIMP_USE_HUNTER
#  include <irrXML/irrXML.h>
#else
#  include <irrXML.h>
#endif
#include "IOStream.hpp"
#include "BaseImporter.h"
#include <vector>

namespace Assimp    {

// ---------------------------------------------------------------------------------
/** @brief Utility class to make IrrXML work together with our custom IO system
 *  See the IrrXML docs for more details.
 *
 *  Construct IrrXML-Reader in BaseImporter::InternReadFile():
 *  @code
 * // open the file
 * std::unique_ptr<IOStream> file( pIOHandler->Open( pFile));
 * if( file.get() == nullptr ) {
 *    throw DeadlyImportError( "Failed to open file " + pFile + ".");
 * }
 *
 * // generate a XML reader for it
 * std::unique_ptr<CIrrXML_IOStreamReader> mIOWrapper( new CIrrXML_IOStreamReader( file.get()));
 * mReader = irr::io::createIrrXMLReader( mIOWrapper.get());
 * if( !mReader) {
 *    ThrowException( "xxxx: Unable to open file.");
 * }
 * @endcode
 **/
class CIrrXML_IOStreamReader : public irr::io::IFileReadCallBack {
public:

    // ----------------------------------------------------------------------------------
    //! Construction from an existing IOStream
    explicit CIrrXML_IOStreamReader(IOStream* _stream)
        : stream (_stream)
        , t (0)
    {

        // Map the buffer into memory and convert it to UTF8. IrrXML provides its
        // own conversion, which is merely a cast from uintNN_t to uint8_t. Thus,
        // it is not suitable for our purposes and we have to do it BEFORE IrrXML
        // gets the buffer. Sadly, this forces us to map the whole file into
        // memory.

        data.resize(stream->FileSize());
        stream->Read(&data[0],data.size(),1);

        // Remove null characters from the input sequence otherwise the parsing will utterly fail
        // std::find is usually much faster than manually iterating
        // It is very unlikely that there will be any null characters
        auto null_char_iter = std::find(data.begin(), data.end(), '\0');

        while (null_char_iter != data.end())
        {
            null_char_iter = data.erase(null_char_iter);
            null_char_iter = std::find(null_char_iter, data.end(), '\0');
        }

        BaseImporter::ConvertToUTF8(data);
    }

    // ----------------------------------------------------------------------------------
    //! Virtual destructor
    virtual ~CIrrXML_IOStreamReader() {}

    // ----------------------------------------------------------------------------------
    //!   Reads an amount of bytes from the file.
    /**  @param buffer:       Pointer to output buffer.
     *   @param sizeToRead:   Amount of bytes to read
     *   @return              Returns how much bytes were read.  */
    virtual int read(void* buffer, int sizeToRead)  {
        if(sizeToRead<0) {
            return 0;
        }
        if(t+sizeToRead>data.size()) {
            sizeToRead = static_cast<int>(data.size()-t);
        }

        memcpy(buffer,&data.front()+t,sizeToRead);

        t += sizeToRead;
        return sizeToRead;
    }

    // ----------------------------------------------------------------------------------
    //! Returns size of file in bytes
    virtual int getSize()   {
        return (int)data.size();
    }

private:
    IOStream* stream;
    std::vector<char> data;
    size_t t;

}; // ! class CIrrXML_IOStreamReader

} // ! Assimp

#endif // !! INCLUDED_AI_IRRXML_WRAPPER